Urea containing fertilizer compositions (e.g., urea fertilizers or urea formaldehyde reaction product fertilizers such as urea-formaldehyde fertilizer or methylene urea fertilizers) have been known and used for many years. Urea containing fertilizers (e.g., urea fertilizers or urea formaldehyde reaction product fertilizers such as urea-formaldehyde fertilizer or methylene urea fertilizers) provide a high level of nitrogen availability, which is necessary to maintain growth and color of lawn turf. Examples of urea containing fertilizers (e.g., urea fertilizers or urea formaldehyde reaction product fertilizers such as urea-formaldehyde fertilizer or methylene urea fertilizers) are disclosed in U.S. Pat. Nos. 3,076,700; 3,231,363; 3,223,518; 4,025,329; 5,102,440; and 6,039,781, each of which are hereby incorporated by reference in their entireties.
Urea containing fertilizers (e.g., urea fertilizers or urea formaldehyde reaction product fertilizers such as urea-formaldehyde fertilizer or methylene urea fertilizers) in general, including solid or granulated urea containing fertilizers, have a tendency to cake or clump over time, such as during storage, causing problems in spreading and/or disseminating the resulting caked or clumped fertilizer products. See U.S. Pat. No. 7,776,125, hereby incorporated by reference in its entirety. Urea containing fertilizers, because they are hygroscopic, develop crystal bridges as they age under typical storage conditions. These crystal bridges result in hard caking and lump formation, thus making the fertilizer more difficult to use effectively. Urea crystal growth is a major component of urea containing fertilizers and one of the important driving forces in the caking process. Urea crystal growth also can develop so extensively that the entire particle surface is covered with urea crystals. When this occurs on fertilizer products containing surface applied active ingredients, overall active ingredient performance can be negatively affected. The net result is lower active ingredient control of weeds or other targeted pests.
Anti-caking agents and crystal modifiers are typically applied directly to the surface urea-containing fertilizers. For example, known anti-caking agents normally have been applied to the surface of the fertilizer particles, and due to inefficient coating techniques, have resulted in only partially coated granules, providing less than effective reduction in caking of the granules. In addition, over time, such surface applied coatings may break away from the granules, and thus the treatment slowly loses effectiveness. WO 2012/129847; U.S. Pat. Nos. 3,041,159; 3,325,276; 3,558,299; 3,852,055; 7,108,732; and 8,492,444, each of which are hereby incorporated by reference in their entireties. These materials have somewhat limited performance because of inefficient coating techniques, resulting in partially coated granules. In addition, over time the surface applied coating may break away from or strike into the granule and thus slowly lose effectiveness.
Solid anti-caking agents found in the art, such as vermiculite, are effective if larger quantities are utilized and the vermiculite is used as a parting agent. But if the vermiculite is granulated and covered with urea containing fertilizer resin, the anti-caking benefits are eliminated.
In sum, anti-caking agents and crystal modifiers known in the art have not satisfactorily solved the caking/clumping problems in urea containing fertilizers (e.g., urea fertilizers or urea formaldehyde reaction product fertilizers such as urea-formaldehyde fertilizer or methylene urea fertilizers).